Should the five days be considered the fixed duration of purity (Tuhr) and bathing done at the scheduled time, or should one wait until seeing the white discharge, regardless of the duration?

What the questioner did upon seeing the returning blood is incorrect. This blood, and any accompanying brownish discharge, is considered menstruation (hayd) because it occurred within a time frame where it can be considered hayd. If a woman sees purity (tuhr) and then blood returns to her within the time frame when menstruation is possible, she is considered to be menstruating again. She is obliged to wait until the blood and any accompanying yellowish or brownish discharge ceases, then perform ghusl (ritual bath). If she sees purity indicated by one of its two signs, she should promptly perform ghusl. Then, if she sees only yellowish or brownish discharge, she should not consider it hayd. However, if she sees blood, she should consider it hayd, along with any accompanying yellowish or brownish discharge, within the possible timeframe. Whenever she doubts whether purity has occurred, the default assumption is that menstruation persists.